Rope Gang / PololuLedStrip

Simple LM35 temperature sensor for adafruit neopixel

Fork of PololuLedStrip by David Grayson

PololuLedStrip.cpp@26:06b316269605, 2017-05-16 (annotated)

Committer:
Conoredwards123
Date:
Tue May 16 01:23:06 2017 +0000
Revision:
26:06b316269605
Parent:
25:d72818ba17cc 
Final

Who changed what in which revision?

UserRevisionLine numberNew contents of line
DavidEGrayson 1:102307d9b701 1 #include "PololuLedStrip.h"
DavidEGrayson 1:102307d9b701 2
DavidEGrayson 1:102307d9b701 3 bool PololuLedStrip::interruptFriendly = false;
DavidEGrayson 1:102307d9b701 4
DavidEGrayson 19:46d7ab0ba3e7 5 // The two timed delays, in units of half-cycles.
DavidEGrayson 19:46d7ab0ba3e7 6 uint8_t led_strip_write_delays[2];
DavidEGrayson 4:d3b60bd43811 7
DavidEGrayson 7:9a088f042ee0 8 void PololuLedStrip::calculateDelays()
DavidEGrayson 7:9a088f042ee0 9 {
DavidEGrayson 15:d69eebdee025 10 int f_mhz = SystemCoreClock / 1000000; // Clock frequency in MHz.
DavidEGrayson 14:672baf3cf941 11
DavidEGrayson 14:672baf3cf941 12 if (f_mhz <= 48)
DavidEGrayson 14:672baf3cf941 13 {
DavidEGrayson 19:46d7ab0ba3e7 14 // The delays below result in 360/1120 ns pulses and a 1880 ns period on the mbed NXP LPC11U24.
DavidEGrayson 14:672baf3cf941 15 led_strip_write_delays[0] = 0;
DavidEGrayson 14:672baf3cf941 16 led_strip_write_delays[1] = 0;
DavidEGrayson 14:672baf3cf941 17 }
DavidEGrayson 14:672baf3cf941 18 else
DavidEGrayson 14:672baf3cf941 19 {
DavidEGrayson 22:5368af3ff07d 20 // Try to generally compute what the delays should be for a wide range of clock frequencies.
DavidEGrayson 14:672baf3cf941 21
DavidEGrayson 14:672baf3cf941 22 // The fudge factors below were experimentally chosen so that we would have
DavidEGrayson 23:881d93b8749a 23 // ~100 ns and ~840 ns pulses and a ~1430 ns period on the mbed NXP LPC1768 (96 MHz Cortex-M3).
DavidEGrayson 17:91fb934a2166 24 // There seem to be some ~100 ns inconsistencies in the timing depending on which example program is
DavidEGrayson 17:91fb934a2166 25 // running; the most likely explanation is some kind of flash caching that affects the timing.
DavidEGrayson 14:672baf3cf941 26 // If you ever change these numbers, it is important to check the the subtractions below
DavidEGrayson 19:46d7ab0ba3e7 27 // will not overflow in the worst case (smallest possible f_mhz).
DavidEGrayson 23:881d93b8749a 28 //
DavidEGrayson 23:881d93b8749a 29 // On an STM32F303K8 (72 MHz Cortex-M4), these delays give us ~170 ns and ~840 ns pulses
DavidEGrayson 23:881d93b8749a 30 // and a ~1595 ns period, and there were no timing differences between the two
DavidEGrayson 23:881d93b8749a 31 // example programs.
DavidEGrayson 19:46d7ab0ba3e7 32 led_strip_write_delays[0] = 750*f_mhz/1000 - 33;
DavidEGrayson 19:46d7ab0ba3e7 33 led_strip_write_delays[1] = 550*f_mhz/1000 - 20;
DavidEGrayson 15:d69eebdee025 34 }
DavidEGrayson 15:d69eebdee025 35
DavidEGrayson 15:d69eebdee025 36 // Convert from units of cycles to units of half-cycles; it makes the assembly faster.
DavidEGrayson 22:5368af3ff07d 37 led_strip_write_delays[0] <<= 1;
DavidEGrayson 22:5368af3ff07d 38 led_strip_write_delays[1] <<= 1;
DavidEGrayson 7:9a088f042ee0 39 }
DavidEGrayson 6:9d0530b7dae2 40
DavidEGrayson 1:102307d9b701 41 PololuLedStrip::PololuLedStrip(PinName pinName)
DavidEGrayson 1:102307d9b701 42 {
DavidEGrayson 22:5368af3ff07d 43 gpio_init_out(&gpio, pinName);
DavidEGrayson 1:102307d9b701 44 }
DavidEGrayson 1:102307d9b701 45
DavidEGrayson 1:102307d9b701 46 void PololuLedStrip::write(rgb_color * colors, unsigned int count)
DavidEGrayson 1:102307d9b701 47 {
DavidEGrayson 8:1578776ceac5 48 calculateDelays();
DavidEGrayson 8:1578776ceac5 49
DavidEGrayson 1:102307d9b701 50 __disable_irq(); // Disable interrupts temporarily because we don't want our pulse timing to be messed up.
DavidEGrayson 7:9a088f042ee0 51
DavidEGrayson 1:102307d9b701 52 while(count--)
DavidEGrayson 1:102307d9b701 53 {
DavidEGrayson 9:6ffb85d69eaf 54 led_strip_write_color(colors, gpio.reg_set, gpio.reg_clr, gpio.mask);
DavidEGrayson 9:6ffb85d69eaf 55 colors++;
DavidEGrayson 9:6ffb85d69eaf 56
DavidEGrayson 1:102307d9b701 57 if (interruptFriendly)
DavidEGrayson 1:102307d9b701 58 {
DavidEGrayson 1:102307d9b701 59 __enable_irq();
DavidEGrayson 1:102307d9b701 60 __nop();
DavidEGrayson 1:102307d9b701 61 __nop();
DavidEGrayson 1:102307d9b701 62 __nop();
DavidEGrayson 1:102307d9b701 63 __disable_irq();
DavidEGrayson 1:102307d9b701 64 }
DavidEGrayson 1:102307d9b701 65 }
DavidEGrayson 1:102307d9b701 66
DavidEGrayson 1:102307d9b701 67 __enable_irq(); // Re-enable interrupts now that we are done.
DavidEGrayson 25:d72818ba17cc 68 wait_us(80); // Send the reset signal.
DavidEGrayson 1:102307d9b701 69 }